Method of assembling relays



Feb. 13, 1962 w. F. DOWDLE 3,020,626

METHOD OF ASSEMBLING RELAYS Original Filed July 22, 1957 2 heets-Sheet 1 FIGJ H FIG.2

Feb. 13, 1962 w. F. DOWDLE 3,02

METHOD OF ASSEMBLING RELAYS Original Filed July 22, 1957 2 Sheets-Sheet 2 so 28 29 I l 24 Ill 1 I l w I 25/ 31 [Ill 1] l i l 32 I8 :7 /L

United States Patent 3,020,626 METHOD OF ASSEMBLING RELAYS Walter F. Dowdle, Lincoln, Ill., assignor to Essex Wire Corporation, Fort Wayne, Ind. Original application July 22, 1957, Ser. No. 673,246, now Patent No. 2,900,472, dated Aug. 18, 1959. Divided and this application Oct. 23, 1958, Ser. No. 772,647

2 Claims- (Cl. 29-1555) This invention relates to an improved construction of an electromagnetic relay and a method of making such a relay. This application is a division of application Serial No. 673,246, filed July 22, 1957, now Patent No. 2,900,472, issued August 18, 1959.

A principal object of this invention is to provide a relay which is rugged, simple, inexpensive to manufacture, assemble, and adjust.

Another object is to provide a relay which can be accurately and uniformly adjusted during its process of manufacture and assembly and before it has been completely assembled.

A further object is to provide a method for assembling a relay which provides for complete adjustment of the relay before the assembly thereof is completed.

Other objects and advantages of the invention will ap pear in the following description and appended claims, reference being had to the accompanying drawings, in which:

FIGURE 1 is a side elevation of a relay embodying the invention.

FIGURE 2 is a top plan view of the relay.

FIGURE 3 is a side elevation similar to FIGURE l v I showing the armature in the attracted position.

FIGURE 4 is a perspective view of the insulating bracket. 7

FIGURE 5 is a side view of the contact spring.

Referring to the drawing, the electromagnetic relay there illustrated and embodying the features of the present invention includes a frame 10 formed from magnetic material and having a base portion 11 and a leg portion 12 bent at right angles to each other. Mounted on the frame base-portion 11 is a coil 13 having a core 14 which is secured to the frame base portion 11 by screw 15. Core 14 is split at its end 16 to accommodate a shading washer 17. For D.C. operation of the coil 13, the core 14 need not be split and the shading washer 17 may be omitted.

An armature 18 extends through an opening 19 provided in the frame leg portion 12 for movement from an unattracted position shown in FIGURE 1 to an attracted position shown in FIGURE 3 when the coil 13 is energized. In the unattracted position, the armature 18 is biased against a stop portion 20 integral with the frame leg portion 12 by spring 21 which is secured to an extending end of armature 18 and to a lug 22 stamped out of the frame leg portion 12.

Secured to the frame leg portion 12 by rivets 23 is an insulating block 24 having a shelf portion 25 extending over the armature 18. Mounted upon the insulating block 24 and extending over the shelf portion 25 are two flexible contact springs 26 carrying movable contacts 27 to engage with and disengage from the fixed contacts 28 located on the shelf portion 25. Circuit connections to suitable conductors may be made by means of screws (not shown) threaded into the terminals 29 which are secured to the contact springs 26 and the fixed contacts 28.

The free ends of the contact springs 26 extend beyond the insulating block shelf portion 25 and are engaged by arm 30 of an insulating bracket 31 attached to the armature 18 by rivets 32 to disengage the movable and fixed contacts 27 and 28 in the unattracted position. The con- 3,020,626 Patented Feb. 13, 1962 tact springs 26 are preformed or bent to produce a desired contact force or pressure between the movable and fixed contacts in the attracted position. In the unattracted position, spring 21 biases. the armature 18 against the stop portion with a greater force than the biasing force of the contact springs 26.

Energization of the coil 13 causes the armature 13 and the arm 30 to move toward the core end 16. As the armature approaches the attracted position, the movable contacts 27 engage-the fixed contacts 28 and the arm 30 separates from the contact springs 26. In the attracted position, the contact pressure between contacts 27 and 28 is determined solely by the biasing force of the contact spring 26. The biasing force of the contact springs 26 aids the movement of the armature 18 in its initial movement toward the attracted position.

After deenergization of the coil 13, the armature 18 and the arm 30 are returned to the unattracted position by spring 21. Because of the separation between the arm 30 and the contact springs 26 in the attracted position, the armature 18 travels a given distance before the arm 30 strikes the contact springs 26. The impact force of arm 30 upon the contact springs 26 is advantageous in that it breaks any contact weld which may have formed between contacts 27 and 28.

By reason of the present construction, the assembly and adjustment of the relay has been greatly simplified. No bending or forming operations are required during or after assembly of the relay to adjust the contact pressure, the contact gap, or the contact closing voltage to within narrow specified limits. By eliminating the manual adjustments normally required, the manufacturing cos of the relay is considerably reduced. I

The only adjustment necessary to obtain consistent contact pressures is performed before assembly of the relay. Before the contact spring 26 is secured to the insulating block 25, its contact carrying end is bent to a specified angle A relative to the opposite end as illustrated in FIGURE 5. It is a relatively simple matter to manufacture the bent contact spring 26 with a high degree of uniformity and a corresponding high degree of uniformity in the contact pressure is obtained.

A consistent contact closing voltage is similarly obtained with no adjustment required during assembly of the relay by manufacturing the frame 10 with the protruding end of the stop portion 20 located at a specified distance from the base portion 11. In the assembled relay, the protruding end of the stop portion 20 will be separated by a required distance from the end 16 of the core 14 which is also easily mnaufactured to have a specified length. Thus the gap between the armature 18 and the core end 16 is easily maintained within narrow limits to provide the relay with armature operating and contact closing voltages within equally narrow limits.

The required separation between the movable and fixed contacts 27 and 28 in the unattracted position is obtained by employing a selected insulating bracket 31 having an arm 30 of the height H necessary to provide the required contact separation. The selected bracket 31 having an arm 30 of the required height H is preferably secured to the armature 18 after the remainder of the relay is assembled. The required height H of the arm 30 may be determined by measuring the separation between the contact springs 26 and the armature 18 in the unattracted position before the bracket 31 is attached. The required bracket arm 30 will have a height greater than the separation by a fixed amount equal to the desired contact separation.

Because the distance of armature travel between the attracted and unattracted positions has an uniform value, the required bracket arm height H may also be determined by measuring the separation between the contact springs 26 and the armature 18 in the attracted position before the bracket Si is attached. The bracket arm 30 is selected to have a height H less by a fixed amount than this separation to provide both a consistent separation between contacts 27 and 28 in the unattracted position and a consistent gap between the arm 30 and the contact springs 26 in the attracted position.

The contact separation in the unattracted position is generally not very critical and it has been found that the separation between armature 18 and the contact springs 26 need not be actually measured, but instead a selected bracket 31is inserted between the armature 1S and the contact springs 26. By visual inspection only, it can be readily determined if the selected bracket provides the desired separation between the contact springs 26 and the arm 30 in the attracted position. Furthermore, the bracket 31 may be selected from a group of brackets 31 having arms 30 varying in height by increments of approximately .015 inch.

-FIGURE 4 illustrates means by which the arms 30 of varying height may be readily distinguished. The brackets 31 are initially molded with all arms 30 having a specified height. On one side of the arms 30 is provided a number of detents or grooves 33 having their bottom portions located at different specified distances from the armature-engaging surface of the bracket 31. When a portion of the spring-engaging surface is removed to provide an arm 30 of a specified height, the number of detents 33 remaining indicates the height of the arm 3%.

While the invention has been illustrated and described in its preferred embodiment and has included certain details, it should be understood that the invention is not to be limited to the precise details herein illustrated and described since the same may be carried out in other ways falling within the scope of the invention as claimed.

What is claimed is:

1. In the assembly of relays of the type which consist of a magnetic frame carrying a core, an electrically energizable winding carried on said core, an armature supported upon said frame and movable from an unattracted position to an attracted position adjacent said core upon energization of said winding, a relatively stationary contact member, a cantilever-supported contact spring extending over said armature and carrying an electric contact arranged for cooperative engagement with said contact member, said contact spring being pretensioned so that it is biased toward the contact member to normally urge said contact into engagement with said contact memher, and a contact actuator having a base portion secured to a surface of said armature facing said freeend of the contact spring and having an actuating face engageable with said free end of the contact spring for displacing said contact spring and said contact away from said contact member in said unattracted position of the armature; the steps comprising: (a) forming a plurality of subassemblies, each comprising said frame, winding, core, armature, contact member, contact spring and contact wherein the spacings between the free ends of the contact springs and the oppositely facing surfaces of the armatures are subject to substantial variation; ([2) forming several groups of actuators, each with a different predeternuned dimension between the actuating faces and the armature-engaging surfaces of the actuators; (c) gauging the spacing between the free end of the contact spring and the oppositely facing surface of the armature of each of said subassemblies; (d) selecting an actuator for each gauged subassembly from the particular one of said groups which actuator, when secured to the armature of said gauged subassembly, gives the closest to a desired separation between the free end of the contact spring and the actuating face of the selected actuator in the attracted position of the armature; and (e) permanently securing each selected actuator to the armature of its corresponding subassembly.

2. In the assembly of relays of the type which consists of a magnetic frame carrying a core, an electrically energizable winding carried on said core, an armature supported upon said frame and movable from an unattracted position to an attracted position adjacent said core upon energization of said winding, a relatively stationary contact member, a cantilever-supported contact spring extending over said armature and carrying an electric contact arranged for cooperative engagement with said contact member, said contact spring being pretensioned so that it is biased toward the contact member to normally urge said contact into engagement with said contact member, and a contact actuator having a base portion secured to a surface of said armature facing said free end of the Contact spring and having an actuating arm with an actuating face engageable with said free end of the contact spring for displacing said contact spring and said contact away from said contact member in said unattracted position of the armature, the steps comprising: (a) forming a plurality of subassemblies each comprising said frame, winding core, armature, contact member, contact spring and contact wherein the spacings between the free ends of the contact springs and the oppositely facing surfaces of the armatures are subject to substantial variation;

(b) forming a plurality of contact actuators with a series of indentations in each actuator having bottom portions located adjacent the end of the actuating arm thereof and at different accurately dimensioned distances from the armature-engaging surface of the base portion thereof; (c) removing different predetermined thicknesses of material from the ends of the actuator arms to provide a plurality of groups of actuators, each with a different number of indentations which indicate the dimension between the actuating face and the armature-engaging surface of the actuator; (d) gauging the spacing between the free end of the contact spring and the oppositely facing surface of the armature of each of said subassemblies; (c) selecting an actuator for each gauged subassembly from the particular one of said groups, which actuator when secured to the armature of said gauged subassembly gives the closest to a desired separation between the free end of the contact spring and the actuating face of the selected actuator in the attracted position of the armature; and (f)- permanently securing each selected actuator to the armature of its corresponding subassembly.

References Cited in the file of this patent UNITED STATES PATENTS Vincent July 21, 1953 

